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Cycloalkanes for AQA GCSE Chemistry

Cycloalkanes

This page covers the following topics:

1. Formulae and solubility
2. First five
3. Molecular formula

Cycloalkanes are hydrocarbons that consist of a ring of carbons with single carbon-carbon bonds. As they contain only carbon and hydrogen they are also not very soluble in water. They generally have slightly higher boiling points than alkanes.

Formulae and solubility

The first 4 clycloalkanes have a different number of carbons to the first 4 alkanes as there MUST be a carbon ring. The minimum number of carbons needed to complete a ring is 3.

First five

Molecular formula shows the number and type of atoms present in a molecule, remember that for alkenes they will follow the general formula from before.

Molecular formula

1

What is the general formula of cycloalkanes?

CnH2n

What is the general formula of cycloalkanes?

2

What is the name of the cycloalkane with the shortest possible carbon chain (the first cycloalkane)?

There must be at least 3 carbons to form a ring, thus it will have 3 carbon atoms.

cyclopropane

What is the name of the cycloalkane with the shortest possible carbon chain (the first cycloalkane)?

3

What is the molecular formula of cyclohexane?

Cโ‚†Hโ‚โ‚‚

What is the molecular formula of cyclohexane?

4

The boiling point point of pentane is 36ยฐC, estimate what the boiling point of cyclopentane is.

49ยฐC (accept anything between 37ยฐ and 67ยฐC)

The boiling point point of pentane is 36ยฐC, estimate what the boiling point of cyclopentane is.

5

How does solubility of cycloalkanes change with chain length?

Shorter cycloalkanes are slightly more soluble than longer chain alkenes

How does solubility of cycloalkanes change with chain length?

End of page

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